Staff and patients were ordered to shelter in place. Police said via Twitter that no victims or injuries have been reported, and they said that there was no confirmation of a gunman. Police said officers are looking for a white male in his mid 30s, weighing about 130 pounds and wearing a flannel shirt and a hat in connection with the situation.

“This is a very fluid situation. It’s an ongoing situation. We are open and ready for however this turns out,” a police spokesman said at a news conference.

All inbound traffic to the hospital has been closed, police said.

Deborah Polhill, a spokeswoman for Rose Medical, said about 4:30 p.m. that the hospital was under a “code silver.”

Polhill said the hospital is on lockdown for a code silver — their code for active shooter.

Melissa Taylor, spokeswoman for the Denver Fire Department, says firefighters are staging at the hospital per their standard response.

“They are actually staged,” Taylor said. “I don’t have any reports of injuries at this point. Last I heard from my crews is that we just have people.”

She added: “We just don’t have enough information right now. The reports were of shots heard. We just got reports of shots heard.”

Dan Warvi, a spokesman for the Veterans Affairs Eastern Colorado Healthcare system including the VA Hospital next to Rose Medical Center, said their building is also on lockdown.

No one is being allowed in or out, and they are monitoring the situation, Warvi said. He said there are no reports of anyone inside the VA buildings shot.

“University of Colorado Hospital is aware of the reported situation, and we are ready to care for patients if needed,” said spokesman Dan Weaver.